Officials from the National Oceanic and Atmospheric Administration’s National Marine Fisheries Service, the U.S. Army Corps of Engineers and the Hawai‘i Department of Land and Natural Resources are working together to try and understand what led to the death of an endangered Hawaiian monk seal on Hawai‘i Island.

The 10-year-old male seal, tagged as RB18, was found dead in a submerged fish pen maintained by Blue Ocean Mariculture in nearshore waters near Keahole Point on March 5, 2017.

Blue Ocean Mariculture reported to NMFS that the pen was emptied of most of the fish and they’d removed a large side panel to allow a shark to escape. The monk seal was reported to NMFS the next day as deceased in the pen.

A necropsy performed on O‘ahu by NMFS veterinarians and biologists concluded the seal drowned, as it had no signs of serious injury or disease.

RB18 was often seen in the area feeding on fish outside the net pen. Its stomach was full of large fish, suggesting that it had foraged very recently prior to its death.

Ann Garrett, assistant regional administrator in the NMFS Protected Resources Division, said, “It is often difficult to determine a precise cause of death for marine mammals because of their complex diving ability, but necropsy observations led to the conclusion that RB18 drowned in the net. We’ve confirmed that this net is now out of service and Blue Ocean Mariculture has removed the top of the pen to further reduce the risk of further entrapments, while the company is in the process of removing the entire pen from the ocean. This is a rare situation and NMFS is investigating the death of the seal.”

In addition to federal permits, Blue Ocean Mariculture has a permit from the State of Hawai‘i.

ADVERTISEMENT

“We are greatly saddened by the death of RB18 but are working together to learn from this tragedy and to minimize any additional impacts to monk seals and other protected marine species that may be associated with offshore aquaculture and the Blue Ocean Mariculture operation,” DLNR Chair Suzanne Case said.

The DLNR Office of Conservation and Coastal Lands is also conducting an investigation and review and will prepare a report with recommendations to avoid this from happening in the future.